When biogas generated from an anaerobic fermentation unit, especially at medium or high temperature, it will carry a large amount of H2S. With the combined action of water and H2S in the biogas, it will accelerate the corrosion and clogging of metal pipes, valves and flow meters. In addition, SO2 will be generated after H2S combustion and it will form� sulfurous acid when� combining with the water vapor in the air, which will cause corrosion on the metal surface of the equipment, and also causes pollution to the atmospheric environment and affects human health. Therefore, H2S in biogas must be removed before it is used.